This research program will examine the social and cognitive processes underlying illness behavior. The theoretical framework for the research is Leventhal's self regulation model of illness behavior. While most psychological investigations of illness cognition and behavior have relied on surveys and correlational data, all of the studies proposed here are laboratory experiments. These studies utilize a recently developed experimental paradigm shown to be useful in recreating many of the psychological phenomena observed in medical patients. The specific focus of these studies is the appraisal process. Subjects will be asked to make judgments of perceived health threats and of their own health under a variety of conditions. Among the possible determinants of health-related judgments to be studied are diagnostic status, affect, and social influence. These latter studies derive and test predictions from social comparison theory to extend the study of illness cognition to social interaction processes. The long-term goal of the project is to produce the basic experimental data needed to formulate a broadened theory of how people cope with medical diagnoses. Furthermore, the project seeks to explore the ways in which the methods of experimental social psychology can be utilized to enrich and clarify the large body of clinical research on coping, symptom reporting, and illness behavior.